A typical wireless network includes multiple wireless stations (wireless devices) communicating wirelessly via wireless media such as one or more radio frequency (RF) wireless channels. Some data applications such as web surfing and e-mail exchange usually require very random wireless channel access with bursty traffic characteristics. In wireless networks with directional transmission, such as in beamforming systems, reserving channel time in advance for these types of data applications leads to low efficiency. Further, it is difficult for two wireless stations to use the same period to communicate with each other since they do not know when to switch their antenna directions to point to each other.